Earth inductor compass



Dec. 9, 1941;

P. F. BECHBERGER 21,970

EARTH INDUCTOR COMPASS 7 Original Filed Dec. 29, 1958 OX \1\ g I FEED/168F987.

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Reiaued Dec. 9, 1941 ma'm mnucroa COMPASS Paul F. Bechberger, 'lenafly, N. 1., assignor to Bendix Aviation Corporation, Bendix, .N. J., a corporation oi Delaware Original No. 2,206,018, dated July 2, 1940, Serial No. 248,335, December 29, 1938. Application for reissue January 9, 1941, Serial No. 373,851

14 Claims.

The present invention relates to-magnetic compasses andmore particularly to earth inductor compasses for remotely indicating the direction of the earth's magnetic field.

One of the objects of the invention is to pro of said E. M. F.s being respectively proportional to the cosine of the angle between the magnetic center line of each coil'or winding and the direction of the earth's magnetic field, means for generating a local single phase E. M. F. simulvide a novel earth inductor compass system taneously with the E. M. F.s generated from the which indicates compass direction throughout earths field and having the same frequency and three hundred sixty degrees (360) without a substantially the same phase as the latter follow-up motor or other additional and com- E. M. 'F.s, means. for amplifying the three plicated mechanisms. E. M. F."s generated from the earths field, and

Another object is to provide an earth inductor compass system comprising a novel remote compass indicator in combination with a novel earth inductor.

A- further object of the invention is to provide a novel earth inductor compass system comprising means including a highly permeable magnetic member having a plurality of pole pieces and provided with a plurality of windings or coils thereon for generating a plurality of alternating current E. M. F.s from the earth's magnetic field, the amplitudes of said E. M. F.s being reone of said members having a plurality of wind- I ings connected in polyphase or polycircuit rela-' tion and respectively energized by the plurality of E. M. F.'s generated from the earths magnetic field, and the other of said members having a single-phase or single circuit winding energized by the single-phase E. M. F. whereby, upon angular displacement of said permeable magnetic member with respect to the earths field, the rotor member of said last'named means is correspondingly displaced by the reaction between the resultant field produced by the plurality of E. M. F.s of the polyphase-connected windings and the field of the single-phase winding of the indicating means to assume an angular position corresponding to the direction of the earths magnetic field. V

A still further object of the invention is to provide a novel earth inductor compass system comprising means including a highly permeable magnetic 'member having three radially extending pole pieces equally spaced angularly and each provided with a winding or coil thereon for generating three alternating current E. M. F.s

from the earths magnetic field the amplitudes indicating means connected to said amplifying means and to said single-phase E. M. F. generating means, said indicating means comprising a stator having three windings connectedln polycircuit or three-phase relation and respectively energized by the three amplified E. M. F.s generated from the earths field, and a rotor having a single circuit or single-phase winding energized by the single-phase E. M. F. whereby, upon angular displacement of said permeable magnetic member with respect to the earths field, the rotor of said indicating means is correspondingly displaced by the reaction between the resultant field produced by the three E. M. F.s of the three-phase-connected stator windings and the field of the single-phase winding to indicate the direction of the earths magnetic field.

The above and other objects and advantages of the invention will appear more fully hereinafter from a consideration of the detailed description which follows, taken together with the accompanying drawin'gwherein one embodiment of the invention is illustrated. It is to be expressly understood, however, that the drawing is for the purposes of illustration and description only, and is not to be construed as defining the limits of the invention, reference being. had for this purpose to the appended claims.

The invention consists substantially in the construction, combination, location and relative arrangement of parts and circuits for obtaining the results desired in accordance with theforegoing objects, as will bemore fully hereinafter set forth in the specification, as shown in the drawing by way of example, and as finally pointed netic field, the amplitude of that ELM. F. will be proportional to the cosine oithe angle between the magnetic center line of the coil and the direction of the earth's field.

The present invention is based upon the abovestated principle and a plurality of coils, in the periodically varying the earth's magnetic fins in the pole pieces 2, I and 4 and, in the form shown,

. said means comprise a rotor 8 also of highly present instancethree coils connected together in polycircuit' or three-phase relation, are provided which are wound on a relatively stationary highly permeable magnetic member having three radially extending pole pieces spaced angularly 120 apart, there being a coil on each pole piece. This magnetic member may be fixed to the craft on which the direction of. the earth's field is to be indicated, with the pole pieces lying in a substantially horizontal plane so as not to be affected by the vertical component the earths field.

An alternating current E. M. F. is'induced in permeable magnetic material such as permalloy, for example, provided with radial projections or pole pieces 9, l0 and II which form air gaps, II, l3-and l4 with the cooperating inner ends of the pole. pieces, 2, I and 4, respectively. The rotor member I is drivably connected to a suitabledriving device such, for example, as an electric motor M for rotation by the latter, as indicated by the dotted line lia representing a drive shaft. Upon rotation of the rotor I the reluctance of the magnetic paths formed by the gaps l2, l3 and I4 is increased and. decreased periodically and thus the flux produced in the pole pieces, I,

each 0! the three coils by the earth's magnetic field by periodically varying the earth's magnetic fiux in the pole pieces of the permeable member in a manner to be described more fully hereinafter, the amplitudes oi said E. M. F.s bein respectively proportional to the cosine 'ot theangle between the magnetic center line of each coil and the directiono! the,earth's field. A local single-phase alternating current E. M. F. is

F.s. The three E. M. F.s generated from the earths magnetic field may then be separately amplified, if desired, by any suitable amplifiers such, for example,.as thermionic vacuum tube amplifiers, and are supplied to an indicator. The

- locally generated single-phase E. M. F. is likealso generated having the same frequency and substantially the same phase as the three E.-M.

wise supplied to the indicator which includes a stator member and a rotor member, one of said members having three windings connected in polycircuit or three-phase relation and respectively energized by the three E. M. F.s generated 'irom the earth's magnetic field, and the other of said members having a-single circuit or singlephase winding energizedby the locally generated single-phase E. M. F. In this manner, when the permeable magnetic member is displaced anguamount corresponding to the angular displaceand 4 by the horizontal component of the earth's field is periodically varied, thereby inducing alternating E. M. F.s in the coils 5, 8. and I, respectively. The amplitudes 01' these E. M. F.s are respectively proportional to the cosine of the angle between the magnetic center line of each coil and the direction oi. the earths field. The

angle between the magnetic center line 01' coil on pole piece 2 and magnetic north is shown at 0.

, The coilsor windings i, l and I are connected in polycircuit or three-phase relation at the iunction point I 6.

If desired, means may be provided-for separately amplifying the E. M. F.s generated in the coils 5, I and I and for this purpose there are shown three vacuum tube amplifiers VT1, We,

.and VTJ. .the inputs or which are respectively.

connected to the coils I, 6 and I, and the outputs of which are connected to the primary windings of transformers T1, T2, and Ta, respectively.

In order to indicate the direction .of the earth's magnetic field, i. 'e., to indicate magnetic north, as .determined by the E. M. F.s generated in the coils 5, land I 01 the earth inductor de- 'vice' I, an indicator is provided which is shown at l1 and which comprises, as shown, an inductive device of the so-called Selsyn or Autosyn type, shown in the patent to E. M. flew-- lett et al No. 1,612,117, for example, and includment of the permeable magnetic member, a

pointer. being connected to the rotor to indicate the angular displacement thereof and, hence, the

direction of the earths field.

Referring now to the single figure of the drawing, the earth inductor device is shown at I and comprises a highly permeable magnetic member constituted, in the present embodiment, by three radially extending pole pieces 2, I and 4,; angularly equally spaced one hundred twenty degrees (120) apart. .The inductor device I is relatively.

stationary and may be fixed to the craft (not shown) on which the direction of the, earth's field is-to be indicated, with the pole pieces arranged in a substantially horizontal plane. Wound on the pole pieces 7., 3 and 4 are'coils or windings 5, B and 1, respectively.

Means arenow provided for generating alternating current E. M. F.s in the coils 5, 6 and 1 respectively, by the earths magneticfield by ing a stator having three windings i8, I! and 2| connected in polycircuit 'or three-phase relation at the junction 2|, and a rotor having a single circuit or single-phase winding 22 and an indicating pointer ll. The single-phase winding 12' is arranged in inductive relation with the threephase-connected windings 18, I9 and II. I

The three amplified E. M. F.s generated by the earth's magnetic field are supplied -respectively to the individual three-ph'ase-connected windings I8, I! and II and for this purpose said windings are connectedto thesecondary wind ings of the transformersTa-Tz. and T3,, respectively. I

The single-phase winding 12 is efiergized by a single-phase alternating current which is generated locally and simultaneously with the three E. M. F.s generated in the coils I. I and 1 Irom the earth's magnetic field, said locally generated alternating current having the same frequency and substantially the same phase as the three E. M. F.s generated from the earth's magnetic field.

,Any suitable generator G may be used for generating the single-phase alternating current for supplying the rotorv winding 22 or the indi-' cator II, but the one shown in the present embodiment is of the type described and claimed in Serial No. 248,344, filed Dec. 29, 1938.

As shown, said generator G comprises. a variable electrostatic condenser having a stationary plate provided with radially extending portions 28, 24 and 25, and a rotatable plate provided with radially extending portions 26, 21 and 28. The rotatable plate is drivably connected to the electric motor M as indicated by the dotted line I51) and, therefore, is rotated at the same speed as the rotor l or the earth inductor device I.

The variable condenser is connected to the input of a thermionic vacuum tube VT; through a fixed condenser C1 and across a resistor R1 and the output 01' the vacuum tube VT4 is connected to the single-phase winding 22 through a transformer T4.

A D. C. charging potential is impressed on the variable condenser through a resistor R2, and the potential across said'resistor R: is periodically increased and decreased by rotation of the rotatable portions 25, 21 and 28 01 the condenser G by the electric motor M. This varying potential is amplified by the vacuum tube VT4, thereby producing a single-phase alternating current in the output of the transformer T4, which current is supplied to the single-phase rotor winding 22 of the remote indicator H by loads 29 and 30, the frequency of said current depending upon the speed of rotation of the rotatable portions 01' the condenser G and being the same as the frequency of the alternating cur,- rents induced in windings 5, 6 and I because the same motor M rotates element 8 as well as condenser G. The phase of these currents is likewise substantially the same.

The resultant field produced by the amplified E. M. F.s in the three-phase-connected windings l8, l9 and 20 is such that the reaction thereof with the field ofthe single-phase rotor winding 22 causes the latter to align itself according to the direction or the earths field as determined by the windings 5, B and I of the earth inductor l, and this direction is indicated by the pointer 3| which is attached to the rotor 22.

There is thus provided a novel earth inductor compass comprising a novel earth indicator and a novel indicator, whereby'the compass direction can be indicated throughout three hundred sixty degrees (360) and without a followup motor or other additional and complicated mechanisms, thereby providing a relatively lightweight compass particularly adapted for use on aircraft.

While only one embodiment of the invention has been illustrated and described, various changes in form, construction and relative arr'angement of parts, which will now appear to gle-phase alternating E. M. I". simultaneously earths field, means for locally generating a sinwith the E. M. 1".s generated from the earth's held and having the same frequency and substantially the same phase as the latter E. M. F.s, and means comprising a rotor member and a stator member, one of said members having a plurality of windings, connected in polyphase M. F.s from the horizontal component of the earths magnetic field, the amplitudes 01' said E.

M. F.'s being respectively proportional to the cosine of the angle between the magnetic center line of each winding and the direction o'f the relation and respectively energized by the E. M. F.'s generated from the earths field in the firstnamed windings and the other 01' said members having a single-phase winding energized by the locally generated single-phase E. M. F. whereby,

I upon angular displacement of said permeable magnetic member with respect to the earths field, the rotor member of said last-named means is correspondingly displaced by the reaction beable magnetic member having three radially extending pole pieces equally spaced angularly and each provided with a winding thereon for generating three alternating E. M. F.'s from the earths magnetic field, the amplitudes of said E. M. F.s being respectively proportional to the cosine of the angle between the magnetic center line of each winding and the direction of the earths field, means for locally generating a single-phase alternating E. M. F. simultaneously with 'the three E. M. F.s' generated from the earths field and having the same frequency and substantially the same phase as the latter E. M. F.'s, means for amplifying the three E. M. F.s

generated from the earths field, and indicating means connected to said ampliiyingmeans and said single-phase E. M. F. generating means, said indicating means comprising a stator having three windings thereon connected in three-phase relation and respectively energized by the three E. M. F.s generated from the earths field in the first-named windings, and a rotor having a single-phase winding thereon energized by the locally generated single-phase E. M. F. whereby, upon angular displacement of said permeable .magnetic member with respect to the earths field, the rotor of said indicating means is correspondingly displaced by the reaction between the sultant field produced by the three E. M. F.s of the three-phase-connected stator -windings and the field of the single-phase winding to indicate the direction of the earths magnetic field.

3.. An earth inductor compass comprising, in

combination, means includinga permeable magearths field, means for locally enerating a single-phase alternating E. M. F. simultaneously with the E. M. F.'s generated from the earths field and having the same frequency and substantially the same phase as'the latter E. M. F.'s, means for amplifying the plurality of E. M. F.'s generated from the earths field in thefirstnamed windings, and indicating means connected tosaid amplifying means and said single-phase E..M. F. generating means, said indicating means comprising a stator having three windings there-- on-colrrnected in three-phase relation and respectively energized by the three E. M. F.s generated from the earth's field in the first-named windings, a rotor having a single-phase winding thereon inductively positioned .with respect to said three windings, said single-phase winding being energized by the locally generated singlephase E. M F. whereby, upon angular displacement of said permeable magnetic member with respect to the earths field, the r dicating meansis correspondingly displaced by roi'said in-' generated from the earth's field and having the same frequency and substantially the same phase in the first-named windings, and a rotor having the reaction between the resultant field produced a by the three F.s oi the three-phaseecone nected stator windings and the field oi the singlephase winding to indicate the direction of the earth's magnetic field.

4. .An earth inductor. compass. comprising, in combination, means including a permeable. magnetic stator member having a plurality of pole pieces and provided with a plurality of' windings thereon, a, highly permeable magnetic rotor member associated with said stator member, means for rotating said rotor member for varythe fiux due to the horizontal component of the earth's magnetic field in said pole pieces to generate a plurality of alternating E. M. F.s in the windings of said stator member, the amplitudes 01' said E. M. F.s being respectively proportional to'the cosine of the angle between the magnetic-center line of each winding and the direction of the earth's magnetic field, means for locally generating a single-phase alternating E.

M. F. simultaneously with the E. M. F.s gener- .ated from the'earth's field and having the same frequency and substantially the same phase as the latter E. M. F.s, and means com'prisinga a single-phase winding thereon energized by the locally generated single-phase E. M. F. whereby, .upon angular displacement of said permeable magnetic member with respect to the earths held, the rotor of said indicating means is correspondingly displaced by the reaction between the resultant field produced by the three E. M. F.s of the three-phase-connected stator windings and the field of the single-phase winding to indicate the direction of the earth's magnetic field.

6. An earth inductor compass comprising, in combination, means including a relatively stationary permeable magnetic member having a 'pluralltyof pole pieces and provided with a plurality of windings thereon for generating a plurality of alternating E.-M. F.s from the horizontal component .of the earth's magnetic field,

'the amplitudes of-said E.M.' F.s being rspectively proportional to the cosine at the angle between the magnetic center line of each winding and the direction of the earths field, means for locally generating .a single-phase alternating E. M. F. simultaneously with the E. M; F.s generated from the earths field and having the same rotor member and a stator member, one oi. said members having a plurality oi windings, connected. in polyphase relation and respectively energized by the E. M. F.s generated from the earth's field in the first-named'stator member, and the other oi said members having a singlephase winding energized by the locally generated single-phase E. M. F. whereby, upon angulardisplacement of said permeable magnetic member with respect to the earth's field, the rotor member of said last-named means is correspondingly displaced by the reaction between the resultant field produced by the plurality or E. M. F.s of

' the polyphase-connected windings, and the field of the single-phase winding of the indicating.

means to assume an angular position correspondingio the direction of the earth's magnetic field.

.5. An earth compass comprising, .in

combination, means including a highly permeable magnetic stator member having three radiirequency and substantially the same phase as the latter E. M. F.s and means comprising a rotor member and. a stator member, one of said member-shaving a plurality of angularly spaced windings, connected in polyp e relation and respectively energized by the M. F.s generdied from the earth's "field in the first-named windings, and the other of said members having a single-phase winding energized by the locally generated single-phase E. M. F. whereby, upon angular displacement of said permeable magnetic member with respect to the earth's field, the rotormember of said last-namedmeans is correspondingly displaced by the reaction between the resultant field produced by the pin rallty of E. M. F.s oithe polyphase-connected .wlndingsand the field o! the single-phase windally extending p'olepieces equally spaced angu- Y 1 larly and each provided with a winding thereon,

a highly permeable magnetic rotor member associated with said stator member, means for driving said rotor member for varying the horizontal component of the fiux due to the earths magnetic field in said polefpieces to; generate three alternating E. M. F.s in the windings of said stator member, the amplitudes of said n. M. F.s being respectively proportional to the cosine of the angle between each pole piece and the direcing of the indicating means to assume an angu lar position corresponding to the direction 0! the earth's magnetic field.

' '1. An earthinductor compass comprising, in combination, means including a permeable magnetic member having a plurality of pole pieces and'provided with a plurality of windings thereon for generating a plurality oi'- alternating E.-M. F.s from the horizontal component of the earth's magnetic field, the amplitude of said E. M. F.s being respectively proportional to the cosine oi the angle between the magnetic center line of each winding and the direction of the earthsfleld, means for generating a single-phase tion of the earth's magnetic field, means simule taneously drivcn'by the rotor driving means for locally generating a single-phase alternating an. r. simultaneously with the three E. M. F.s

alternating E. M. E. having the same frequency and substantially the same phase as the E. M. F.s

generated from the earth's field, and means comprising a rotor member and a stator member, one of said members having a' plurality of windings associated therewith and connected in polyphase relation and respectively energl'zed by the E. M. F.s generated from the earth's field. in the first-named windings and the other said members having a single-phase winding associated therewith and energized by the single-phase E. M. F. whereby, upon angular displacement of said permeable magnetic member with respect to the earths field, the rotor member of said last-named means is correspondingly displaced to assume an angular position corresponding to the direction of the 'earths magnetic field.

8. An earth inductor compass comprising, in

combination, means including a permeable nfagnetic member provided with a plurality of windings thereon for generating a plurality of alter- .earths field in the windings of said permeable magnetic member, and the other of said members having a single-phase winding associated therewith and energized by the single-phase E. M. F. whereby, upon angular displacement of said permeable magnetic member with respect to the earths field, the rotor member of said lastnamed means is correspondingly displaced to assume a position corresponding to the direction of the earths magnetic field.

9. A magnetic compass comprising an inductive device having ,a stator member and a rotor member in an inductive relation with each other, one of'said members having a polyphase winding and the other having a single-phase winding, indicating means drivably connected to said rotor member for actuation thereby, a source of alternating E. M. F. connected to energize said single-phase winding, direction responsive means comprising an induction device including a permeable mag netic core member havinga plurality of windings thereon connected in polyphase relation and adapted to be traversed by a uni-directional magnetic field for generating a plurality of alternating E. M. F.s having the same frequency as said first alternating E. M. F., and means connecting the windings of said induction device to energize the polyphase winding oi said inductive device bysaid plurality of E. M. F.s, whereby the rotor member oi said inductive device rotates to actuate said indicating means upon relative angular movement in azimuth between said permeable core member and said uni-directional magnetic field.

10. A magnetic compass comprising an inductive device having a stator member and a rotor member in inductive relation with each other, one

ing, direction responsive means comprising an induction device including a permeable magnetic core member having a polyphase winding thereon and adapted to be traversed by a uni-directional magnetic field for generating a plurality of periodically varying E. M. F.s of the same frequency of variation as'said first E. M. F.. and means connecting the polyphase winding or said induction device to energize the polyphase winding 01 said inductive device by said plurality of E. M. F.s, whereby the rotor member of said inductive device rotates to actuate said indicating means upon relative angular movement in azimuth between said permeable core member and said uni-directional magnetic field.

11. In combination, an inductive device having a stator member and a rotor member in inductive relation with each other, one or said members having a polyphase winding and the other having a single-phase winding, means connected to said rotor member for actuation thereby, a source of periodically varying E. M. F. having a predetermined frequency of variation and connected to energize said single-phase winding, magnetic direction responsive means comprising an induction device including a permeable magnetic core member disposed in a horizontal plane, and having a polyphase winding thereon and adapted .to be traversed by a uni-directional magnetic field for generating a plurality of periodically varying E. M. E's of the same frequency as said first E. M. F., and means connecting the polyphase winding of said induction device to energize the polyphase winding of said inductive device by said plurality of E. M. F.s, whereby the rotor member of said inductive device rotates to actuate the means connected thereto upon relative angular movement between said permeable core member and said uni-directional magnetic field. 12. An earth inductor compass comprising, in combination, means including a permeable magnetic member provided with a plurality of windlugs-thereon for generating a pluralitypf alternating E. M. F.s from the horizontal component i of the earth's magnetic field, means for generating a single-phase alternating E. M. F. .having the same frequency and substantially the same phase, as the E. M. F.s generated from the earths field, and means comprising a rotor member and a stator member, one of said members having a plurality of windings associated therewith and connected in polyphase relation andrespectively,

energized by the E. M. F.s generated from the earths field in the windings of said permeable magnetic member, and the other of said members having a singlephase winding associated therewith andenergized by the single-phase E. M. F.

whereby, upon angular displacement of said perearth's field before energizing said polyphaseconnected windings.

13. In combination, an inductive device having a stator provided with a polycircuit winding and a rotor provided with a single circuit winding,

. means drivably connected to said rotor for actuation thereby, a source of periodically varying E. M. F. connected to energize said single circuit winding, direction responsive means remote from said inductive device and comprising an induc- .tion device including a plurality of cores of magi'or generating a plurality of periodically varying polycircui't stator winding of saidinductive device by said plurality 01 E. M. R's whereby 'the rotor 01, said inductive device rotates to actuate the means connected thereto upon relative angular movement between said induction device and said uni-directional magnetic field. v

14. A remote indicating magnetic compass comprising an inductive device having a stator termined angular relation about a common center and having a plurality oi output windings thereon interconnected in polycircuit relation and adapted to be traversed by a uni-directional magnetic field for generating a plurality of periodically varying E. M. R's having the same frequency oi variation as said first E. M. F.. and

. means connecting the windings oi said induction provided with a polycircuit winding and a rotor provided with a single circuit winding, indicating means drivably connected to said rotor for actuation thereby, a source of periodically varying E. M. F. connected to energize said single circuit winding, direction responsive. means remote from said inductive device and comprising aninduction device including a plurality of cores 01 magnetically permeable material arranged in prededevice to energm the polycircuit. stator winding of said inductive device by said plurality of E. M. F.s whereby the rotor of said inductive device rotates to actuate said indicating means upon relative angular movement between said induction device and said uni-directionalmagnetic 

